Embryo Project Encyclopedia Articles

Isotretinoin is a molecule and a byproduct (metabolite) of vitamin A, and in greater than normal amounts in pregnant women, it can cause fetal abnormalities including cleft lips, ear and eye defects, and mental retardation. Isotretinoin is commonly called by its trade name Accutane, and it's a chemical compound derived from vitamin A, or retinoic acid. Doctors prescribe isotretinoin to treat severe acne. For pregnant women, too much vitamin A or isotretinoin can also cause greater than normal rates of stillbirths and fetal disintegrations after the ninth week of gestation. Women who use isotretinoin during the first trimester of their pregnancies, even in small amounts, risk defects to their fetuses such as external ear malformations, cleft palates, undersized jaws (micrognathia), a variety of heart defects, buildups of fluids inside the skulls that leads to brain swelling (hydrocephalus), small heads and brains (microcephaly), and mental retardation.

Thomas Joseph King Jr. was a developmental biologist who, with fellow scientist Robert Briggs, pioneered a method of transplanting nuclei from blastula cells into fresh egg cells lacking nuclei. This method, dubbed nuclear transplantation, facilitated King's studies on cancer cell development. King's work was instrumental for the development of cloning of fish, insects, and mammals.

'On the Permanent Life of Tissues outside of the Organism' reports Alexis Carrel's 1912 experiments on the maintenance of tissue in culture media. At the time, Carrel was a French surgeon and biologist working at the Rockefeller Institute in New York City. In his paper, Carrel reported that he had successfully maintained tissue cultures, which derived from connective tissues of developing chicks and other tissue sources, by serially culturing them. Among all the tissue cultures Carrel reported, one was maintained for more than two months, whereas previous efforts had only been able to keep tissues in vitro for three to fifteen days. Carrel’s experiments contributed to the development of long-term tissue culture techniques, which were useful in the study of embryology and eventually became instrumental in stem cell research. Despite later evidence to the contrary, Carrel believed that as long as the tissue culture method was accurately applied, tissues kept outside of the organisms should be able to divide indefinitely and have permanent life.

The p53 protein acts as a pivotal suppressor of inappropriate cell proliferation. By initiating suppressive effects through induction of apoptosis, cell senescence, or transient cell-cycle arrest, p53 plays an important role in cancer suppression, developmental regulation, and aging. Its discovery in 1979 was a product of research into viral etiology and the immunology of cancer. The p53 protein was first identified in a study of the role of viruses in cancer through its ability to form a complex with viral tumor antigens. In the same year, an immunological study of cancer also found p53 due to its immunoreactivity with tumor antisera. Although a series of studies found p53 through various routes, and various researchers called it different names, it was eventually confirmed that they had all encountered the same protein, p53.

Infantile Autism: The Syndrome and Its Implications for a Neural Theory of Behavior (hereafter Infantile Autism) is a book written by Bernard Rimland, published in 1964. The book proposed a theory to explain the causes of autism. The book also synthesized research into autism and used Rimland's neural theory, described in the book, as a theory to explain some aspects of behavior, intelligence, and abnormality. Moreover, Infantile Autism contributed to a debate between Rimland and child psychologist Bruno Bettelheim in the 1960s over whether autism was caused by upbringing (see refrigerator mother theory) or by impaired brain development. Rimland's book convinced many autism researchers to look for abnormal psychological development.

Leo Kanner published Autistic Disturbances of Affective Contact in 1943 in the journal Nervous Child. This article described the cases of eleven children with autism. Kanner described the behavior and upbringing of each child, aged two to eight, as well as the educational backgrounds of the children's. Though Eugen Bleuler, a professor of psychiatric at the University of Z rich and director of the Burgh lzli Asylum in Z rich in Z rich, Switzerland from 1898 to 1927, was first to use the term autism to describe of a symptom of schizophrenia, scientists cite Kanner's article as the first description of autism as a unique disease concept distinct from schizophrenia. One of the most cited articles about autism in the twentieth century, this article was the first to demarcate Kanner syndrome, which later called childhood autism. Researchers, including Kanner, eventually treated early infantile autism as a disorder resulting from abnormal development of the autistic children's brains.

In 1943, child psychiatrist Leo Kanner in the US gave the first account of Early Infantile Autism that encouraged psychiatrists to investigate what they called emotionally cold mothers, or refrigerator mothers. In 1949, Kanner published Problems of Nosology and Psychodynamics of Early Infantile Autism. In that article, Kanner described autistic children as reared in emotional refrigerators. US child psychiatrists claimed that some psychological or behavioral conditions might have origins in emotional or mental stress, meaning that they might be psychogenic. Kanner described autism's cause in terms of emotional refrigeration from parents into the early 1960s, often attributing autism to the lack of parental warmth. In the 1960s, Bernard Rimland in the US and Bruno Bettelheim in Austria disagreed on the role of psychogenesis in autism. Rimland suggested that autism's cause was rooted in neurological development, while Bettelheim continued to emphasize the role of nurturing during early childhood. Nevertheless, many mothers reported that they felt a deep sense of anguish and resentment toward child psychiatrists who often made them feel as if they were to blame for their children's autism.

In a series of experiments between 1960 and 1965, Robert Geoffrey Edwards discovered how to make mammalian egg cells, or oocytes, mature outside of a female's body. Edwards, working at several research institutions in the UK during this period, studied in vitro fertilization (IVF) methods. He measured the conditions and timings for in vitro (out of the body) maturation of oocytes from diverse mammals including mice, rats, hamsters, pigs, cows, sheep, and rhesus monkeys, as well as humans. By 1965, he manipulated the maturation of mammalian oocytes in vitro, and discovered that the maturation process took about the same amount of time as maturation in the body, called in vivo. The timing of human oocyte maturation in vivo, extrapolated from Edwards's in vitro study, helped researchers calculate the timing for surgical removal of human eggs for IVF.

In the early 1960s, John W. Saunders Jr., Mary T. Gasseling, and Lilyan C. Saunders in the US investigated how cells die in the developing limbs of chick embryos. They studied when and where in developing limbs many cells die, and they studied the functions of cell death in wing development. At a time when only a few developmental biologists studied cell death, or apoptosis, Saunders and his colleagues showed that researchers could use embryological experiments to uncover the causal mechanisms of apotosis. The researchers published many of their results in the 1962 paper 'Cellular death in morphogenesis of the avian wing.'

Sir John Bertrand Gurdon further developed nuclear transplantation, the technique used to clone organisms and to create stem cells, while working in Britain in the second half of the twentieth century. Gurdon's research built on the work of Thomas King and Robert Briggs in the United States, who in 1952 published findings that indicated that scientists could take a nucleus from an early embryonic cell and successfully transfer it into an unfertilized and enucleated egg cell. Briggs and King also concluded that a nucleus taken from an adult cell and similarly inserted into an unfertilized enucleated egg cell could not produce normal development. In 1962, however, Gurdon published results that indicated otherwise. While Briggs and King worked with Rana pipiens frogs, Gurdon used the faster-growing species Xenopus laevis to show that nuclei from specialized cells still held the potential to be any cell despite its specialization. In 2012, the Nobel Prize Committee awarded Gurdon and Shinya Yamanaka its prize in physiology and medicine for for their work on cloning and pluripotent stem cells.